Smooth transition catheters

ABSTRACT

The present invention generally relates to a rapid exchange configuration that reduces the profile of a catheter riding on a guidewire and minimizes guidewire resistance. According to certain embodiments, a body of the catheter includes a distal portion and a proximal portion. The distal portion defines a guidewire lumen and includes a guidewire exit port being open in an proximal direction and leading to the guidewire lumen. A proximal section of the guidewire lumen is straight.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/108,609, filed Dec. 17, 2013, now issued as U.S. Pat. No. 10,595,820,which claims the benefit of and priority to U.S. Provisional Ser. No.61/739,855, filed Dec. 20, 2012, each of which is incorporated byreference in its entirety.

TECHNICAL FIELD

The present application generally relates rapid exchange configurationfor catheters. The invention provides enhanced designs that improvetransitions between components of catheter.

BACKGROUND

Intraluminal devices, such as guidewires and catheters, allow for avariety of disorders of the endovascular to be evaluated and treatedwithout creating an open surgical field. Endovascular procedurestypically include passing a guidewire through an access artery (e.g.brachial, femoral, radial) and to a vessel of interest within thevasculature. Once the guidewire is in place, a catheter is guided overthe guidewire to perform an intraluminal procedure at the vessel ofinterest. An intraluminal procedure may require the introduction andexchange of several specialized catheters into the vasculature, whichcan lead to lengthy procedure times. As a result, changes have been madeto the design of the catheters in order to improve their exchangeabilityand reduce procedure length.

A known catheter design for reducing procedure time is a rapid exchangeconfiguration, which includes a guidewire lumen that only extendsthrough the distal portion of the catheter. Prior to rapid exchangeguidewire lumens, catheters often included an over-the-wire lumen thatextended the entire length of the catheter device. Due to the longlumen, an over-the-wire catheter requires a guidewire more than twicethe length of the catheter. This allows a physician to maintain a gripon the ex vivo portion of the guidewire when exchanging catheters. Thelong guidewire is cumbersome to handle, causes clutter, and often slowsdown an already lengthy procedure.

In contrast, a rapid exchange catheter has a guidewire lumen that onlyextends through the distal portion of the catheter. A typical knownrapid exchange configuration includes a substantially L-shaped lumenthat begins at a distal tip of the catheter and ends at a guidewire exitport, which is located on a side of the distal portion of the catheterand faces the vessel surface. In this configuration, the guidewirepasses through the catheter shaft only for a segment of the length ofthe shaft, and the catheter can be moved along the guidewire in“monorail” fashion. Because the guidewire lumen is considerably shorterthan the overall length of the catheter, a shorter guidewire can beused. For easy handling, the guidewire simply has to be long enough sothat the length of the guidewire protruding from the patient is longerthan the length of the guidewire lumen of the catheter. This ensures aportion of the guidewire is exposed at all times and may be grasped bythe physician.

The current rapid exchange configuration suffers from some drawbacks,however. The rapid exchange design requires a portion of the guidewireto bend within the L-shaped guidewire lumen to exit the guidewire exitport located on the side of the catheter. In addition, the guidewiremust bend again once out of the guidewire exit port in order to extendparallel to the proximal portion of the catheter. Because the guidewireexits the side of the catheter and then extends in parallel to thecatheter, this configuration increases the vessel diameter requirements(i.e. the vessel must fit the combined diameters of the catheter and theguidewire).

In addition, the various bending of the guidewire may provide pushissues or track issues with the catheter as it is being driven over theguidewire. A push issue arises when a proximal portion of a catheter ispushed further into the entry vessel and a distal end does not move thecorresponding distance. A track issue arises when the proximal portionis torqued and the distal end does not rotate as expected. Pushing andtracking properly are crucial in negotiating the difficult curves orobstructions in the vasculature.

Thus, there is a need for a rapid exchange catheter with a low profilethat reduces guidewire resistance.

SUMMARY

The invention provides catheters having a guidewire exit port that isopen in the proximal direction and a substantially straight guidewirelumen. Catheters of the invention allow rapid guidewire exchange andminimal guidewire resistance. Because the guidewire lumen issubstantially straight, the guidewire is not required to bend in orderto exit the guidewire lumen or bend in order to extend along theproximal portion of the catheter within the vessel. This eliminatesguidewire resistance as the catheter is being guided on the guidewireand provides better push and tracking characteristics. In addition, withthe rapid exchange configuration of the invention, the exposed guidewireextends parallel to the proximal portion of the catheter withoutincreasing the profile of the combined catheter and guidewire.

According to certain aspects, a catheter with the rapid exchangeconfiguration of the invention includes a proximal portion and a distalportion. The distal portion defines a guidewire lumen, in which aproximal portion of the guidewire lumen is substantially straight. Thedistal portion also includes a guidewire exit port being open in aproximal direction and leading to the guidewire lumen. The guidewireexit port is configured to receive a guidewire running parallel to theproximal portion. In some embodiments, the distal portion has across-section larger than a cross-section of the proximal portion. Inthis manner, the combined profile of the guidewire and the proximalportion is the same as or smaller than the profile of the distal portionof the catheter. As a result, the portion of the guidewire exiting thedistal portion does not increase the vessel diameter requirements.

A catheter with the rapid exchange configuration according to certainembodiments is constructed from a first shaft coupled to a second shaft.The coupled first shaft and second shaft form at least part of thecatheter body. The first shaft includes a skived proximal portion anddefines a first lumen. The skived proximal portion includes a guidewireexit port being open in the proximal direction. The second shaftincludes a skived distal portion and defines a second lumen. The skiveddistal portion of the second shaft is coupled to the skived proximalportion of the first shaft such that the first lumen and the secondlumen form a continuous lumen. In some embodiments, the continuous lumenincludes the guidewire lumen, and the guidewire exit port leads to aportion of the continuous lumen. In other embodiments, the first shaftincludes a guidewire lumen separate from the continuous lumen, and theguidewire exit port leads to the guidewire lumen.

Concepts of the invention can be applied to any type of catheter.Suitable catheters include, for example, imaging catheters, deliverycatheters, and interventional catheters. In particular embodiments, acatheter including concepts of the invention is an imaging catheter. Theimaging catheter may include an imaging element positioned on the distalportion of the catheter. The imaging element is a component of animaging assembly. The imaging assembly can be an ultrasound assembly oran optical coherence tomography assembly.

Other and further aspects and features of the invention will be evidentfrom the following detailed description and accompanying drawings, whichare intended to illustrate, not limit, the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 depicts a prior art catheter.

FIG. 2A depicts the distal end of a proximal portion of a catheter.

FIG. 2B depicts the proximal end of a distal portion of a catheter.

FIG. 2C depicts a proximal portion of FIG. 2A coupled to the distalportion of FIG. 2B via a butt joint.

FIG. 2D depicts a cross-sectional view of the proximal portion of FIG.2A.

FIG. 2E depicts a cross-sectional view of the distal portion of FIG. 2B.

FIG. 3A depicts a section of a foundation hypotube of a catheter.

FIG. 3B depicts a section of an intermediate hypotube of a catheter.

FIG. 3C depicts the intermediate hypotube of FIG. 3B overlapping thefoundation hypotube of FIG. 3A to form the distal and proximal portionsof varying flexibility.

FIG. 3D depicts a cross-sectional view of the proximal portion of FIG.3A.

FIG. 3E depicts a cross-sectional view of the distal portion of FIG. 3B.

FIG. 4 depicts an exemplary phased-array IVUS catheter with the rapidexchange configuration of the invention according to certainembodiments.

FIG. 5A shows the transition between a distal portion and a proximalportion of a catheter having the rapid exchange configuration of theinvention according to certain embodiments.

FIG. 5B illustrates a cross-sectional view of the proximal portion shownin FIG. 5A.

FIG. 5C illustrates a cross-sectional view of the distal portion shownin FIG. 5A.

FIG. 5D illustrates a distal-facing view of the proximal portionextending proximally from the distal portion as shown in FIG. 5A.

FIG. 5E shows an alternative embodiment of the transition between thedistal portion and proximal portion of the catheter shown in FIG. 5A.

FIG. 5F shows the distal end of the proximal portion of a catheteraccording to certain embodiments of the invention.

FIG. 5G shows the proximal end of the distal portion of a catheteraccording to certain embodiments of the invention.

FIG. 5H illustrates a skive cut of a proximal portion of the inventionaccording to certain embodiments.

FIG. 5I illustrates a skive cut of a distal portion of the inventionaccording to certain embodiments.

FIG. 6A shows the transition between a distal portion and a proximalportion of a catheter having the rapid exchange configuration of theinvention according to other embodiments.

FIG. 6B illustrates a cross-sectional view of the proximal portion shownin FIG. 6A.

FIG. 6C illustrates a cross-sectional view of the distal portion shownin FIG. 6A.

FIG. 6D illustrates a distal-facing view of the proximal portionextending proximally from the distal portion as shown in FIG. 6A.

FIG. 6E shows the distal end of the proximal portion of a catheteraccording to certain embodiments of the invention.

FIG. 6F shows the proximal end of the distal portion of the catheteraccording to certain embodiments of the invention.

FIG. 6G illustrates a skive cut of a proximal portion according tocertain embodiments of the invention.

FIG. 6H illustrates a skive cut of a distal portion according to certainembodiments of the invention.

DETAILED DESCRIPTION

The present invention discloses a rapid exchange configuration forcatheters that provides the desired combination of a low profilecatheter/guidewire system with minimal to no guidewire resistance. Acatheter with the rapid exchange configuration of the inventiongenerally includes a guidewire exit port being open in the proximaldirection and leading to a substantially straight guidewire lumen. Theproximally facing guidewire exit port and the substantially straightguidewire lumen allow the guidewire to remain straight as it passesthrough the guidewire lumen. This eliminates the bending of the requiredby contemporary rapid exchange guidewire lumens. Instead, with the rapidexchange configuration of the invention, the guidewire is able tosmoothly transition into and out of the guidewire lumen. The smoothtransition of the guidewire reduces guidewire resistance and improvescatheter tracking and push capabilities.

As discussed in the Background, current rapid exchange configurationssuffer from two major drawbacks. First, the guidewire is required tobend as it extends out of the guidewire exit port and along a proximalportion of the catheter. Second, because the guidewire exit port islocated on the side of the catheter, a portion of the guidewireextending out of the guidewire exit port and next to the catheter bodyincreases vessel diameter requirements. For example, the vessel musthave a diameter sufficient to support both the full diameter of thecatheter and the full diameter of the guidewire running in parallel tocatheter. In order to better understand aspects and benefits of thecurrent invention, a brief discussion of prior art rapid exchangecatheters and the various mechanical elements thereof, in general, isprovided below.

FIG. 1 depicts a prior art catheter. As shown in FIG. 1, the catheterincludes a proximal portion and a distal portion. The catheter is shownwith a guidewire disposed therein. The catheter rides along theguidewire extending through the distal portion. A portion of theguidewire exits through a guidewire exit port and extends along theproximal portion of the catheter.

A common problem of prior art catheters is their rapid exchangeconfiguration, which is highlighted in the area enclosed by circle K ofFIG. 1. The rapid exchange configuration includes the shape of the rapidexchange guidewire lumen and the location of the guidewire exit port.Because the guidewire exit port is located on a side of the catheterbody, the guidewire lumen requires a bend to direct the guidewire fromthe distal tip to the guidewire exit port. The bend ultimate causes aguidewire extending through the lumen to bend. In addition, the locationof the guidewire exit port requires the guidewire to bend again uponexiting the guidewire exit port so that the guidewire extends paralleland alongside catheter body. FIG. 2C highlights the contemporaryguidewire lumen and guidewire exit port. The distal portion 15 includesguidewire lumen 6. The guidewire lumen 6 includes bend 17 and leads toguidewire exit port 2 located on the side of the distal portion 15. Theguidewire 50 extending through the lumen 6 and out of the guidewire exitport 2 must bend twice 21 and 23 in order to run alongside the proximalportion 13. This bending of the guidewire can cause resistance againstthe catheter as it is pushed distally along or rotated with respect tothe guidewire, which may result in push and tracking issues.

Most catheters include at least one inner lumen, in which one or morefunctional elements are housed or driven there through. For example,imaging catheters often utilize the inner lumen to house transmissionlines that connect an imaging element located on the distal end of thecatheter to an imaging instrument connected to a proximal end of thecatheter. Delivery catheters, on the other hand, often use the innerlumen to contain an implant deployment mechanism. For example, a pushrod can be driven through the inner lumen to distally deploy an implantout of a distal end of the catheter and into a vessel. Aspirationcatheters utilize the inner lumen as an aspiration channel, throughwhich debris and blood clots can be removed from the vessel.

The proximal portion and the distal portion of most catheters act tocreate a catheter body of variable stiffness and flexibility. The distalportion is typically quite flexible. The proximal portion, as shown inFIG. 1, may include a stiff section A and an intermediate section B,which has flexibility somewhere between the stiff portion and a flexibledistal portion. Alternatively, the proximal portion may be a hypotube ofuniform flexibility. The stiffness/flexibility is shown graphically nextto each section as correlation between load and lateral displacement.The stiff portion A includes a small correlation between load andlateral displacement. In other words, when a transverse force is exertedon the proximal end, the proximal end only flexes a small amount. Incontrast, the distal end is quite flexible and experiences a largeamount of lateral displacement with a relatively small amount of appliedload.

In order to create the catheter body of varying stiffness andflexibility, the catheter is generally formed from a combination ofcomponents fused together or overlapping. That, the stiff portion,intermediate section, and the distal portion are often separateindividual tubes or parts that are fused together or overlapped to formthe elongate catheter body with desired mechanical properties. Forexample, the stiff portion of many catheters includes a stiff hollowtube (hypotube) that is only slightly flexible and has excellentcompressional strength, allowing a physician to deliver force laterallyalong the catheter. Hypotubes may be constructed from standard metals,such as stainless steel, or from memory metals, such as nitinol, analloy of nickel and titanium. Hypotubes may also be constructed frompolymers such as the polymer sold under the trademark PEBAX®, nylon,HDPE, and the polymer sold under the trademark PEEK. The intermediatesections are often also hypotubes and are constructed from polymers withmoderate stiffness, such as polyamides, to provide transitionalflexibility between the proximal and distal ends. The distal end of theintraluminal device is typically constructed from a flexible polymerhypotube with good kink resistance, such as a fluoropolymer.

A common design consideration for joining portions of a catheterincludes aligning lumens of the individual sections. For example, inorder to create a continuous inner lumen extending the entire length ofthe catheter, the lumens of the individual sections must be aligned.Another design consideration is the tensile strength of catheter at thejoint between two different portions. A catheter design havinginsufficient tensile strength can result in catheter failure. Forexample, when catheter is under tension while being proximally retractedfrom within the patient's body lumen, a catheter body havinginsufficient tensile strength may partially or completely tear at thejoint between two portions. This can result in the potentially lethaldislocation of the catheter distal portion.

Another design consideration for joining the distal and proximalportions of the catheter includes the rapid exchange profile of thecatheter. The rapid exchange profile is the combined profile of both theguidewire and catheter having a rapid exchange configuration. One mustconsider the catheter diameter and the diameter of the guidewire whendetermining whether the system can enter a vessel of interest. Vesselsof interest are often inherently small and can have further reduceddiameters due to the build up of atheroma material such as plaque. Assuch, it is desirable to have a small rapid exchange profile, so thatthe catheter can access more vessels. The type of transition can affectthe overall rapid exchange profile of the catheter.

The following describes common ways for transitioning between the distaland proximal portions of varying flexibility, which is also the portionof the catheter enclosed by the circled K of FIG. 1. The resulting rapidexchange profile is also discussed.

One known way to transition between the distal and proximal portions ofa catheter is to form a butt joint. A butt joint is formed by abuttingthe flat ends of the distal and proximal portions squarely together.Generally, an intermediate hypotube of the proximal portion is coupleddirectly coupled to a flexible hypotube of the distal portion and thenfused together to form a continuous elongate catheter body. FIGS. 2A-2Edepict formation of a butt joint between a flexible distal portion and astiffer proximal portion of a catheter. FIG. 2A shows the distal end 10of a proximal portion 13 with an inner lumen 4. FIG. 2D shows across-sectional view of the proximal portion 13 at the y-axis of FIG.2A. FIG. 2B shows a proximal end 20 of the distal portion 15 with aninner lumen 8 and a guidewire lumen 6. FIG. 2E shows a cross-sectionalview of the distal portion 15 at the y-axis of FIG. 2B. The guidewirelumen 6 includes a bend 17 that leads to a guidewire exit port 2 on aside of the distal portion 20. To form the butt joint, a distal surface10 a of the proximal portion 13 is placed flush against a proximalsurface 20 a of the distal portion 15, as shown in FIG. 2C. The innerlumen 4 of the proximal portion 13 is matched up against the inner lumen8 of the proximal portion 10. Once properly abutted, the proximalportion 13 is fused to the distal portion 15 using known catheter fusingtechniques.

FIG. 2C also shows the rapid exchange profile of the catheter with thebutt joint configuration. As shown, a portion of the guidewire 50 isextending through the guidewire lumen 6. Another portion of theguidewire 50 exits through the guidewire exit port 2 and is extendingparallel to the proximal portion 13. Because the guidewire 50 exits theside of the distal portion, the rapid exchange profile includes thediameter of both the guidewire and the catheter. That is, the rapidexchange profile includes the diameter (L) of the catheter plus thediameter (G) of the guidewire (L+G).

A problem associated with the butt joint design is that the butt jointhas a low tensile strength, and therefore poses a risk of joint failureand dislocation of the distal portion. An alternative design fortransitioning between the distal and proximal portions that providesvariable flexibility and a high tensile strength is an overlappingdesign. The overlapping design includes overlapping hypotubes orapplying coating layers to create the flexible distal portion and thestiffer proximal portion. For example, a flexible hypotube extending thefully length of the catheter is provided as a foundation. To create anintermediate proximal section (Section B in FIG. 1), a polymer coatingor hypotube is placed over a portion of the flexible hypotube leavingonly the distal portion exposed. This creates the flexible distalportion and an intermediate proximal portion. To create the stiffproximal section (Section A in FIG. 1), an additional polymer coating orhypotube is placed over the proximal end of the proximal portion leavingthe intermediate proximal section B exposed.

FIGS. 3A-3E depict formation of an overlapping transition between aflexible distal portion and a stiffer proximal portion of a catheter.FIG. 3A shows a foundation hypotube 30. Although not shown, thefoundation hypotube 30 extends the entire length of the catheter body.The foundation hypotube 30 includes an inner lumen 22 and a guidewirelumen 32. FIG. 3E shows a cross-sectional view of the foundationhypotube 30 at the y-axis of FIG. 3A. FIG. 3B shows an intermediatehypotube 40. The intermediate hypotube 40 can be used to create theintermediate section B of the proximal portion (See FIG. 1). Theintermediate hypotube 40 includes a center lumen 42. FIG. 3D shows across-sectional view of the intermediate hypotube 40. To form thecatheter with varying flexibility, the foundation hypotube 30 isdisposed within the center lumen 42 of the intermediate hypotube 40,leaving the distal portion of the foundation hypotube 30 exposed, asshown in FIG. 3C. The foundation hypotube 30 and the intermediatehypotube 40 can be fused together with heat or by adhesive. The exposedfoundation hypotube 30 forms flexible distal portion 33 and theoverlapping hypotubes 30 and 40 form the intermediate proximal portion35. Instead of the using an intermediate hypotube 40, the intermediateproximal portion 35 can be formed by applying a polymer coating to thefoundation tube 30, leaving the distal portion exposed.

FIG. 3C also shows the rapid exchange profile of the catheter with theoverlapping configuration. Like the butt-joint design, the catheterguidewire 50 exits the side of the distal portion and extends along thelength of the proximal portion of the catheter. However, the overlappingcatheter body has a larger diameter as compared to the butt-jointconfiguration because the profile of the proximal portion includes thediameter (L) of the foundation catheter body plus the thickness (S) ofthe intermediate hypotube. Thus, the overall rapid exchange profileincludes the diameter (L) of the foundation hypotube 30, the thickness(S) of the intermediate hypotube 40, and the diameter (G) of theguidewire 50.

While the overlapping design provides a catheter having variableflexibility with high tensile strength, the overlapping configurationundesirably increases the rapid exchange profile. Because of theincreased rapid exchange profile, the overlapping design limits theaccessibility of the catheter within the vasculature.

Catheters of the invention overcome the shortcomings of the prior art byproviding a substantially straight guidewire lumen and a proximallyfacing guidewire exit port. In addition, some embodiments of the presentinvention include a smaller rapid exchange profile than possible withthe prior art catheters. Furthermore, certain embodiments achieve thesmaller rapid exchange profile while also maintaining the high tensilestrength between a flexible distal portion and a stiffer proximalportion.

The concepts of the invention may be applied to any intraluminalcatheter, which may include intravascular catheters and urologicalcatheters. In certain embodiments, the concepts of the invention areapplied to rapid exchange catheters, which have guidewire lumens onlyextending in the distal portion. A catheter of the invention may be animaging catheter, a delivery catheter, or an interventional catheter.Delivery catheters typically deliver a medical device (e.g. stent,filter, or plug) into the body. Interventional catheters are often usedto morcellate or ablate diseased tissue. Catheter bodies intended forintravascular introduction, will typically have a length in the rangefrom 50 cm to 200 cm and an outer diameter in the range from 1 French to12 French (0.33 mm: 1 French), usually from 3 French to 9 French. In thecase of coronary catheters, the length is typically in the range from125 cm to 200 cm, the diameter is preferably below 8 French, morepreferably below 7 French, and most preferably in the range from 2French to 7 French. A distal portion of a catheter may range from 5 cmto 25 cm and a proximal portion may range from 50 to about 200 cm.Intermediate sections of the proximal portion may range from 25-125 cm.

In some embodiments, the catheter will be an imaging or sensingcatheter. Imaging catheters allow a physician to acquire images oftissues from within a lumen, e.g., a blood vessel. Often it isinstructive to image a tissue prior to treatment, e.g., with angioplastyor drugs. The image may be obtained with acoustic waves, i.e.,ultrasound, or the image may be obtained with light. Thus, the inventionincludes intravascular ultrasound (IVUS), optical coherence tomography(OCT), and intravascular magnetic resonance imaging (IVMRI), in additionto other intravascular imaging techniques. Systems for IVUS arediscussed in U.S. Pat. No. 5,771,895; U.S. Pub. 2009/0284332; U.S. Pub.2009/0195514 A1; U.S. Pub. 2007/0232933; and U.S. Pub. 2005/0249391, thecontents of each of which are hereby incorporated by reference in theirentirety. The imaging catheters may use any configuration, such asphased array, forward-looking, rotational pullback, etc. Sensingcatheters, such as flow (Doppler), pressure, temperature, or bloodoxygenation-sensing catheters will also benefit from variable stiffnessmidsections.

An exemplary phased-array IVUS catheter with the improved rapid exchangeconfiguration of the invention is illustrated in FIG. 4. The areaenclosed by circle F highlights the transition between the distalportion and proximal portion and a rapid exchange configuration of theinvention. Various embodiments of the transition between the distalportion and the proximal portion and embodiments of the rapid exchangeconfiguration of the invention are described hereinafter.

FIG. 5A shows the transition between a distal portion 105 and a proximalportion 110 of a catheter having the rapid exchange configurationaccording to one embodiment. The distal portion 105 and the proximalportion 110 can be formed from one continuous shaft or two shaftscoupled (e.g. fused) together at a joint. As shown, the distal portion105 and the proximal portion 110 are two separate shafts coupledtogether to form the catheter body. Preferably, the distal portion 105is a flexible hypotube fabricated from a flexible polymer (as discussedpreviously), and the proximal portion 110 is a hypotube of moderatestiffness (such as the previously discussed hypotubes for theintermediate section B).

As discussed, certain aspects of the invention involve forming a jointbetween a shaft of the distal portion 105 and a shaft of the proximalportion 110 to create the rapid exchange configuration shown in FIG. 5A.FIG. 5F shows a distal end 110 a of the shaft of the proximal portion110 according to certain embodiments. The proximal portion 110 definesan inner lumen 122 and includes a distal end 110 a. FIG. 5G shows aproximal end 105 a of the shaft of the distal portion 105 according tocertain embodiments. The distal portion 105 defines an inner lumen 124and a guidewire lumen 126. To form the catheter body, the distal end 110a of the proximal portion 110 is coupled to the proximal end 105 a ofthe distal portion 105. Preferably, the distal portion 105 and theproximal portion 110 are joined so that the inner lumen 124 of thedistal portion 105 and the inner lumen 122 of the proximal portion 110align to form the continuous lumen shown in FIG. 5A.

A diameter L2 of the proximal portion 110 is smaller than the diameter Lof the distal portion 105. This orientation allows a section of thedistal portion 105 to extend vertically (in the y-direction) beyond theproximal portion 110 as joined to the distal portion 105. The extendedsection of the distal portion 105 forms the proximal face 114 of thedistal portion 105. FIG. 5B illustrates a cross sectional view of theproximal portion 110 as shown in 5A. FIG. 5C illustrates a crosssectional view of the distal portion 105 as shown in FIG. 5A. FIG. 5Dillustrates a distal-facing view of the proximal portion 110 extendingproximally from the distal portion 105 as shown in 5A. As shown in FIG.5D, the cross-section of the proximal portion 110 completely aligns witha section of the distal portion 105. In this manner, the maximumdiameter of the combined proximal and distal portions is the diameter Lof the distal portion 105.

As discussed, the section of the distal portion 105 extending verticallyabove the proximal portion 110 (i.e. the section of the distal portion105 that is not directly aligned with and facing the proximal portion110) forms the proximal face 114 of the distal portion 105. The proximalface 114 defines a guidewire exit port 130, which leads to guidewirelumen 126. FIG. 5E depicts another embodiment of the proximal face 114that has been angled to provide a smoother device profile.

As shown in FIG. 5A, the guidewire exit port 130 is open in the proximaldirection and leads to a guidewire lumen 126. In certain embodiments, atleast the proximal portion of the guidewire lumen 126 is substantiallystraight. In certain embodiments, the entire length of the guidewirelumen is substantially straight 126. Alternatively, a distal portion ofthe guidewire lumen may slight curve to, for example, combine theguidewire lumen 126 with the continuous lumen or provide a guidewireentry port at the center of a distal tip of the device.

A benefit of the proximally facing guidewire exit port 130 leading to asubstantially straight guidewire lumen 126, as shown in FIGS. 5A and 5E,is that the guidewire 50 does not have to bend to exit the guidewirelumen 126. In addition, the guidewire 50 does not have to bend afterexiting the guidewire exit port to extend alongside the proximal portion110. Rather, the guidewire 50 maintains a substantially straight shapeas it extends through the guidewire lumen 126 and out of the guidewireexit port 130. This configuration reduces resistance of the guidewire 50as the catheter is driven over the guidewire 50 in the distal orproximal directions.

Another benefit of the catheter design shown in FIGS. 5A and 5E is therapid exchange profile (i.e. the combined profile of the catheter andguidewire). Because the rapid exchange configuration does not requirethe guidewire 50 to exit through a guidewire exit port located on theside of the distal portion 105, the guidewire 50 does not increase therapid exchange profile of the device. Rather, the guidewire 50 exitsproximally from the guidewire exit port 130 in a linear fashion and runsparallel and along the proximal portion 110. Thus, the rapid exchangeprofile of the device equals the diameter L of the distal portion 110.As a result, devices having this rapid exchange configuration of theinvention have an overall lower profile than the prior art rapidexchange catheters shown in FIGS. 1, 2C and 3C. The lower profile allowsa physician to access the smaller vessels of the vasculature with ease.

In addition, the distal portion 105 and the proximal portion 110 of theembodiment shown in FIGS. 5A and 5B, define at least one inner lumenthat extends continuously between the distal portion and the proximalportion 110. The inner continuous lumen may extend the entire length ofthe catheter. The continuous lumen may provide any function, such ashousing the transmission lines to provide energy to an imaging element,sensor, or ablation element located at the distal end of the device andto return signals from any of those elements. As another example, thecontinuous lumen can be used to house a morcellating tool that can beextended out of the distal end of the catheter to morcellate diseasedtissue.

FIG. 6A shows the transition between a distal portion 105 and a proximalportion 110 of a catheter having the rapid exchange configurationaccording to another embodiment. The distal portion 105 and the proximalportion 110 can be formed from one continuous shaft or two shaftscoupled (e.g. fused) together at a joint. As shown, the distal portion105 and the proximal portion 110 are two separate shafts coupledtogether to form the catheter body. Preferably, the distal portion 105is a flexible hypotube fabricated from a flexible polymer (as discussedpreviously), and the proximal portion 110 is a hypotube of moderatestiffness (such as the previously discussed hypotubes for theintermediate section).

As discussed, certain aspects of the invention involve forming a jointbetween a shaft of the distal portion 105 and a shaft of the proximalportion 110 to create the rapid exchange configuration shown in FIG. 6A.FIG. 6E shows the shaft of the proximal portion 110 according to certainembodiments. The proximal portion 110 defines an inner lumen 122 andincludes a distal end 110 a. FIG. 6F shows the shaft of the distalportion 110 according to certain embodiments. The distal portion 105defines an inner lumen 124. In this aspect, the inner lumen 124 is theguidewire lumen and forms the continuous lumen between the distalportion 105 and proximal portion 120. In addition, the distal portion105 includes a proximal end 105 a. To form the catheter body, the distalend 110 a of the proximal portion 110 is coupled to the proximal end 105a of the distal portion 105.

A diameter L2 of the proximal portion 110 is smaller than the diameter Lof the distal portion 105. In addition, the inner lumen 124 of thedistal portion 105 is larger than the inner lumen 122 of the proximalportion 105. Also, the distal portion 105 and the proximal portion 110are joined so that the inner lumen 124 of the distal portion 105 atleast partially aligns with the inner lumen 122 of the proximal portion110 to form the continuous lumen shown in FIG. 6A. This orientationallows a section of the distal portion 105, which includes a section ofthe inner lumen 124, to extend vertically (in the y-direction) beyondthe proximal portion 110 as joined to the distal portion 105. Theextended section of the distal portion 105 forms the proximal face 114of the distal portion 105. An extended section of the inner lumen 124forms a guidewire opening 130 on the proximal face 114.

The guidewire opening 130 leads to the inner lumen 124 of the distalportion 124, which is a part of the continuous lumen. Thus, in thisembodiment, the inner lumen 124 of the continuous lumen is also theguidewire lumen. Merging the guidewire lumen with the inner lumenreduces the complexity of the shaft of the distal portion 105. Insteadof a shaft with a separate guidewire lumen and a separate inner lumen, acommon hypotube with a single lumen can be used. In other words, thedesign shown in FIG. 6A does not require that the distal portion 105include a guidewire lumen separate from the inner lumen 124, and thedesign can be made with standard commercially available hypotubes.

FIG. 6B illustrates a cross sectional view of the proximal portion 110shown in FIG. 6A. FIG. 6C illustrate a cross sectional view of thedistal portion 105 shown in FIG. 6A. FIG. 6E shows a distal-facing viewof the proximal portion 110 extending proximally from the distal portion105 shown in FIG. 6A. As shown in FIG. 6D, the cross-sectional view ofthe proximal portion 110 completely aligns with a section the distalportion 105. In this manner, the maximum diameter of the device is thediameter L of the distal portion 105. As discussed, the section of thedistal portion 105 extending vertically above the proximal portion 110(i.e. the portion is not directly aligned with and facing the proximalportion 110) forms the proximal face 114 of the distal portion 105. Theproximal face 114 defines a guidewire exit port 130, which leads toinner lumen 124 of the continuous lumen. The proximal face 114 as shownin FIG. 6A may be angled like the proximal face as shown in FIG. 5E toprovide a smoother device profile.

As shown in FIG. 6A, the guidewire exit port 130 is open in the proximaldirection and leads to inner lumen 124 of the continuous lumen. Incertain embodiments, at least the proximal portion of the inner lumen124 is substantially straight. In certain embodiments, the entire lengthof the inner lumen 124 is substantially straight. Alternatively, adistal portion of the inner lumen 124 may slight curve to provide aguidewire entry port at the center of a distal tip of the device.

A benefit of the proximally facing guidewire exit port 130 leading tothe substantially straight inner lumen 124 of the continuous lumen, asshown in FIG. 6A, is that the guidewire 50 does not have to bend to exitthe inner lumen 124. In addition, the guidewire 50 does not have to bendafter exiting the guidewire exit port to extend alongside the proximalportion 110. Rather, the guidewire 50 maintains a substantially straightshape as it extends through the inner lumen 124 and out of the guidewireexit port 130. This configuration reduces resistance of the guidewire 50as the catheter is driven over the guidewire 50 in the distal orproximal directions.

Another benefit of the catheter design shown in FIG. 6A is the rapidexchange profile (i.e. the combined profile of the catheter andguidewire). Because the rapid exchange configuration does not requirethe guidewire 50 to exit through a guidewire exit port located on theside of the distal portion 105, the guidewire 50 does not increase therapid exchange profile of the device. Rather, the guidewire 50 exitsproximally from the guidewire exit port 130 in a linear fashion and runsparallel and along the proximal portion 110. Thus, the rapid exchangeprofile of the device equals the diameter L of the distal portion 110.As a result, devices having this rapid exchange configuration of theinvention have an overall lower profile than the prior art rapidexchange catheters shown in FIGS. 1, 2C and 3C. The lower profile allowsa physician to access the smaller vessels of the vasculature with ease.

In certain embodiments, the invention provides for joining the distalportion 105 and the proximal portion 110 in a segmented fashion. Forexample, the distal portion 105 and the proximal portion 110 are shownjoined in a segmented fashion in FIGS. 5A, 5E, and 6A. In order toproduce a segmented joint of the invention, the distal portion 105 andthe proximal portion 110 are skived in a complementary orientation thatallows the proximal end 105 a of the distal portion 105 to overlap withthe distal end 110 a of the proximal portion 110. Skiving means cuttingout a notch across the hypotube, and is best exemplified in FIGS. 5H,5I, 6G, and 6H. Preferably and as shown, the notch is sliced off distalportion 105 and the proximal portion 105 at a 90.degree. angle (shown asQ). However, other angles can be used, including 91.degree.-135.degree.angles.

Due to the skiving of the distal portion 105 and the proximal portion110, a plurality of complementary binding surfaces are formed that actto strengthen the joint between the distal portion 105 and proximalportion 110. For example, skived distal end 110 a of the proximalportion 110 includes binding surfaces 111 a, 112 a, and 113 a that arecomplementary to the binding surfaces 111 b, 112 b, and 113 b of theskived proximal end 105 a of the distal portion 105, respectively (SeeFIGS. 5H, 5I, 6G, and 6H). To form the segmented joint, the bindingsurfaces of the proximal portion 110 are coupled to their complementarybinding surfaces of the distal portion 105. The more complementarybinding surfaces, the greater the tensile strength of the joint betweenthe distal portion 105 and proximal portion 110. The resulting joint ofthe distal portion 105 and the proximal portion 110 is shown as boldedline 180 in FIGS. 5A, 5E, and 6A.

Any technique known in the art can be utilized to couple the proximalportion to the distal portion of the catheter. Typically, the variousshafts of a catheter are coupled via heat fusing. An exemplary techniquefor fusing includes holding the shafts of the distal portion and theproximal portion together and placing one or more mandrels within theinner lumen and/or guidewire lumen. The mandrels are preferably theshape and size of the lumens and are coated with a non-stick coating.The non-stick coating can be a polytetrafluoroethylene (PTFE) or aparalene coating. With the distal and proximal portions held togetheralong with the mandrels disposed therein, heat is applied to the jointof the distal and proximal portions, thereby fusing the shafts together.Once the shafts are fused together, the mandrels are removed, and theouter portion of the joint can be shaped as desired to form a smooth,consistent joint. One example of shaping includes angling the proximalend face of the distal portion as shown in FIG. 5C.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patentapplications, patent publications, journals, books, papers, webcontents, have been made throughout this disclosure. All such documentsare hereby incorporated herein by reference in their entirety for allpurposes.

EQUIVALENTS

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects illustrativerather than limiting on the invention described herein. Scope of theinvention is thus indicated by the appended claims rather than by theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. An intraluminal catheter, comprising: a catheterbody configured to be positioned within a body lumen of a patient,wherein the catheter body comprises a proximal portion coupled to adistal portion, a first side, and an opposite second side, wherein theproximal portion comprises a first material, a first diameter, a firstouter surface, wherein the distal portion comprises a different secondmaterial, a second diameter, a second outer surface, wherein the firstdiameter is smaller than the second diameter, wherein the first outersurface of the proximal portion and the second outer surface of thedistal portion are aligned on the first side of the catheter body,wherein the first outer surface of the proximal portion and the secondouter surface of the distal portion are unaligned on the second side ofthe catheter body by the first diameter of the proximal portion and thesecond diameter of the distal portion, wherein the first diameter of theproximal portion defines a space for a guidewire to extend alongside thefirst material of the proximal portion and outside of the catheter bodyon the second side of the catheter body, wherein the second diameter ofthe distal portion defines a guidewire lumen for the guidewire to extendalongside the second material of the distal portion and inside of thecatheter body on the second side of the catheter body, wherein theguidewire lumen defined by the second diameter is aligned with the spacefor the guidewire defined by the first diameter, wherein the secondmaterial defines the second outer surface of the distal portion, theguidewire lumen, and an inner lumen distinct from the guidewire lumen,wherein a portion of the second material is disposed between theguidewire lumen and the inner lumen along an entire length of theguidewire lumen, wherein an opening of the guidewire lumen islongitudinally co-located with a transition between the first materialof the proximal portion and the second material of the distal portion.2. The intraluminal catheter of claim 1, wherein the first material ofthe proximal portion defines an additional inner lumen continuous withthe inner lumen.
 3. The intraluminal catheter of claim 1, wherein adistal end of the proximal portion and a proximal end of the distalportion are skived, and wherein the skived ends are coupled.
 4. Theintraluminal catheter of claim 3, wherein the coupling comprises a heatfusion joint.
 5. The intraluminal catheter of claim 1, wherein theguidewire lumen is arranged such that the guidewire can enter, extendthrough, and exit the guidewire lumen without bending.
 6. Theintraluminal catheter of claim 1, wherein the proximal portion isarranged such that a combined diameter of the guidewire and the proximalportion is the same as or smaller than the second diameter of the distalportion.
 7. The intraluminal catheter of claim 1, wherein the cathetercomprises an imaging catheter, a delivery catheter, or an interventionalcatheter.
 8. The intraluminal catheter of claim 1, wherein the firstmaterial comprises a first polymer and the second material comprises asecond polymer different from the first polymer.
 9. The intraluminalcatheter of claim 8, wherein the distal portion is more flexible thanthe proximal portion.
 10. The intraluminal catheter of claim 8, whereinthe second material comprises a kink-resistant polymer.
 11. Theintraluminal catheter of claim 1, wherein a cross section of the firstmaterial at a joint between the first material and the second materialis different than cross sections of the first material proximal to thejoint.
 12. The intraluminal catheter of claim 1, wherein a cross sectionof the second material at a joint between the first material and thesecond material is different than cross sections of the second materialdistal to the joint.